Calculating machine



Dec. 5, 1944. H, LUHN 2,364,540

CALCULATING MACHINE Filed Oct. 10, 1942 7 SheesSheet' l FIGJV. E

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ATTORNEY Dec. '5, 1944. H. P. LUHN 2,354,540

CALCULATING MACHINE Filed Oct. 10, 1942 v SheetsSheet s /62 ll/a llama/P505 ATTORNEY FIGA:

A BY

Dec. 5, 1944. H. P. IQ. UHN 2,364,540

CALCULATING MACHINE Filed Oct. 10, 1942 '7 Sheets-Sheet 4 FIGA-a.

A'II'TORNEY Dec. 5, 1944. H. P. LUHN CALCULATING MACHINE Filed Oct. 10, 1942 '7 Sheets-Sheet 5 F'IG .410.

' ATTORN EY 7 Sheets-Sheet 6 1/ m 9 a 7 5 4 a 2 1 o lNVE TO ATTORNEY H. P. LUHN CALCULATING MACHINE Filed Oct. 10, 1942 d e i .7 I48 Dec. 5, 1944.

Dec. 5, 1944. P, LUHN 2,364,540

CALCULATING MACHINE Filed 001;. 10, 1942 TSheets-Sheet '7 l5//5/2///0.98 765 452- I0 'ATTORNEY Patented Dec. 5, 1944 UNITED CALCULATING MACHINE Hans P. Luhn, Armonk, N. Y., assignor to Inter! national Business Machines Corporation, New York, N. Y., a corporation of New York Application October 10, 1942, Serial No. 461,560

27 Claims.

This invention relates to calculating machines and more particularly to machines of the type ilaihat are electrically operated under control of eys.

The principal object of the invention is to provide an improved electrical accumulator wherein each denominational order comprises a set of four electromagnetic switches or relays, upon which the digits are represented combinationally in accordance with the binary system of notation.

A further object is to provide controls for the relays whereby adding or subtracting may be performed selectively and to provide indicating devices upon which the balance standing in the accumulator is displayedtogether with the algebraic sign of such balance.

A more specific object resides in the-provision of mechanism which ascertains the algebraic sign of the amount standing in the accumulator, the

algebraic sign of the amount to be entered and the relative values of the two amounts, and which mechanism, from these three determinations, ascertains the algebraic sign of the result of the calculation prior to its performance.

A further object is to provide an accumulator the amount entering keys.

Fig. 2 is a detail of one of the accumulating relay magnets in its unset position,

Fig. 3 is adetail of one of the accumulating relay magnets in its set position,

Figs. 4, 4a and 4b taken together andlaced side by side in the order named, constitute a wiring diagram of the electric circuits of the machine for handling decimal amounts.

Fig. 5 is a chart showing the relationship of the accumulating relays for successive amount entries.

Fig. 6 is a chart showing the relationship of accumulating and entering relays for a problem involving a carry-on-carry condition.

Figs. 7 and 7a taken together show the wiring of two orders of the machine in which each order may be adjusted to handle various fractions.

In carrying out the objects of the invention, each denominational order of the accumulating mechanism comprises four so-called accumulating relay devices, each of which has a value assi ned thereto in accordance with the first four terms of the binary progression, namely, 1, 2, 4 and 8. The relays each have a set and an "unset position with an entry in any one thereof being represented by its set condition. Accordingly, any number from 1 to 15 can be represented by the setting of one or more of the relays.

For each denominational order there is provided a set of four so-called entering relays which also have the values of the binary progression assigned thereto. These latter relays are energized in combinational manner to represent an amount to be entered and for each order such amount may also be from 1 to 15 which is the capacity of the four value combination 1, 2, 4, 8.

In the operation of the devices, with the accumulating relays set to represent an amount, an amount to be entered is set on the entering relays. Both kinds of relays consequently effect the adjustment of a system of contacts or switches, so electrically interconnected that a continuous circuit is established through all denominational orders which causes the accumulating relays to assume a setting representing the sum or difference of the two amounts. I

Amounts to be subtracted are set up on the entering relays in the form of complements of where X represents a set condition for a binary term. If to this there is to be added a number such as 007, which is represented as 84218421 -xxx 4 we would find that upon addition in each order separately the results 0 9 10 expressed as To adjust this to the true result 100, inspection will show that a 6 must be added in the right hand order to bring this to zero, a 7 must be added in the central order to bring it to zero, and a 1 must be added in the left hand order to bring it to 1. Such entries are represented by ---x -xxx -xxwhich, if each order is separately added, will resultin the true result.

---18 (complement) XXXX XXX XXX Separately added they give XXX X X X X Correctives li,0,-4 X X -X X RcsultOOO X--X The correctives in any case are not entered as such but are taken into account in the arrangement of the device to route the accumulating circuit through a path determined by the nature of the problem.

The operations just mentioned relate to a decimal accumulator. When any order of the accumulator is to be used in accumulating fractions whose denominator is 2, 3. 4, 5. 6. 7. 8. 9. 11, 12, 13, 14 or 15, a knob or dial related to that order is initially adjusted to a position corresponding to the fraction selected. Such setting has the effect of modifying the accumulating circuit connections to take into account whatever correctives are called for in handling the selected fractions. To illustrate the requirements, assume the handling of the units, yards, feet and inches. Then, one order of the accumulator is set to handle twelfths, another thirds and the last tenths, and

an entry of 3 yards, 2 feet and 12 inches would be represented as follows:

As a further illustration, assume the handling of pints, quarts and packs, in which case the fractions are halves, eighths and tenths,'and an entry of 2 peeks, 6 quarts and 1 pint would be represented as follows: I

Peeks Quarts Pints 842184218421 2-6-1 --X-XX---X Adding0-7-i XXX X Sum without corrcct ivcs X -X X X -X Corrcctivcsl,9,l-i -XX XXXX ResultS-(Hl --XX-XX-- For subtracting operations we have Iecks l Quarts Pints ,s421s4218421 2-0-1 .--x--Xx----X Suhtracting0-71(complements) X X X X X X X X Diilvrcnce without correctivos -XXXX. XXX Corrcctivcs 6,-i4 X X X Rcsultl-Hl -XXXX- In the drawings Figs. 4,. 4a and 4b together show the wiring of the apparatus for handling only tenths and decimals which will first be described to point out the principles of operation. Figs. 7 and 7a together show the universal wiring arrangement which includes settable devices for selectively handling any of several fractions in the two orders shown. This arrangement will be described later to point out wherein the difierences between the two lies, which dilference as explained is found in the routing of the wiring connections to take the appropriate correctives into account.

For each accumulator orde'r there is provided a series of numeral representing lamps constituting a readout device. Through contacts adjustably set by the accumulating relays in an order, the lamp corresponding to the value standing in the order is illuminated to indicate the true value of the amount set on the relays. A pair of plus and minus sign indicating lamps are also provided to indicate the algebraic sign of the indicated amount. a

Before describing the circuits, a brief description will be given of the keyboard construction and of the accumulating relays.

Keyboard of keys. Each key I is provided with a locking pin 4 which, when the key is depressed, rocks the related bar 3 toward the left to release any previously latched keys. Upon such depression, the bar 3 under the influence of its spring I snaps back over the pin 4 of the depressed key. Each of the digit keys i is provided with a set or setsof contacts, generally designated a and b in Fig. 1, with one of the blades curved and inclined as indicated at 8 for cooperation with a stud or roller I on the key stem i. The portion 8 acts as a return spring for the key set so that, when released, the pressure of the spring 6 against stud I will elevate the k..y to its normal position.

In the case of the zero 'key, no contacts are provided and the spring 6 shown serves to restore this key to normal position. The zero key serves as a clearing key.

The several contacts associated with the keys are shown diagrammatically in Figs. 4, 4a and 4b, where the complete set of keys for three orders is shown. The three sets of keys and their related contacts are all alike, and similar reference numerals are employed to designate the like parts. Directly beneath each key are contacts a, hand arranged to convert the digit into a binary equivalent directly or in the form of a complement. The circuits involved will be more vspecifically pointed out in connection with the circuit diagram.

Accumulating relay One of the accumulating relays is shown in Fig. 2 where the parts are shown in normal or unset position. This relay comprises a magnet generally designated A mounted on the frame H! to which there is pivoted an armature 8 at the point 9 and a bell crank lever ill at the point ll.

-'Energization of the magnet A will rock armature 8 counterclockwise against the tension of spring l2. This action will draw lever I3 to the left so that a spring I'I will rock the lever about its pivot '23 on armature 8 to the dotted line position shown in Fig. 2. Pivoted to extension Ha of the frame I4 is a T-shaped lever I5 which is rotatable on the pin IS. The spring I! is connected between the extremity I8 of lever I5 and a pin 99 on the lever I3 and serves to engage hook 20 of lever [B to hold it in the position shown in Fig. 2, where a pin 22 bears against the upper end of bell crank l0, holding it in the clockwise position shown, so that its other arm holds the contact blades a, b, c, in cated.

When magnet A is energized and lever 63 rocked to its dotted line position, the lever I3 is brought into engagement with the upper hook 2| of lever I5 and the spring I! holds the parts in this position as long as magnet A remains energized. Upon deenergization of the magnet, its spring 12 will return armature 8 and at the same time will rock levers l3 and IE to the position shown in Fig. 3, in which position the spring ll will .now hold the parts until magnet A is again energized. In this position the pin 22 and a second pin 24 have moved to permit th bell crank lever In to rock counterclockwise and enable the contacts associated therewith to take an alternate position as shown.

When magnet A is again energized, the lever l3 will swing back into engagement with the hook 20 and upon deenergization of the magnet the armature l2 will force lever l3 against the hook 20 and the pin'22 will rock the bell crank i0 clockwise back to the position of Fig. 2. In this position it may be noted the pin 24 serves to lock the bell crank it against counterclockwise movement.

For each denominational order of the mechanism there are four relays such as shown in Fig. 2, each controlling a plurality oi contacts which are specifically designated in the circuit diagram where their purpose will be explained.

Referring to Fig. 4, the four A relay magnets are designated Al, A2, A4 and A8 and above the magnets are contacts arranged along a horizontal dotted line with the contacts designated by a lower case letter. The A magnets are each provided with a plurality of windings represented by diagonal lines. The passage of current through the relative positions indiany one of these windings is sufficient to energize the magnet and effect a shift inthe position of the related contacts. It is to be borne in mind in following the subsequent explanation that the actual shifting of the contacts occurs upon deenergization of the magnet and that upon energization, the shifting levers merely move into position to prepare for the actual shifting of the contacts.

Operating keys In Fig. 4 are three keys diagrammatically represented and designated as I09, H0 and HI. The key I l I is used for zeroizing or resetting purposes and upon depression closes a related pair of contacts designated illa. The key H0 is depressed when a subtracting operation is to be performed. This key also closes a pair of related contacts designated 0a. The key I09 is depressed when an amount is to be added. This key closes a pair of contacts designated N911 and in addition, through bell crank levers designated H2 and H3 will draw rods indicated at Ill and M5 to the left as viewed in Fig. 4. These rods interconnect the blades of a series of contacts to effect a displacement thereof when the key N19 is operated. These contacts will be specifically identified and their purpose explained in connection with the tracing of circuits therethrough.

Circuit diagram In' the circuit diagram are represented the four accumulating relay magnets Al, A2, A4 and A8 for each of the three orders shown together with the several windings for these magnets. The contacts controlled by the magnets are designated a, b, c, d, e, etc., and in the tracing of circuits through these contacts they will be designated by the reference character of the magnet followed by the letter of the particular contact and also followed by the letter L or R to indicate whether the movable blade of the contact is in its left hand or right handposition. Thus, for example, the designation A8bR denotes the b contacts of the A8 relay magnet in its right hand position. This system of identification of the contacts is utilized to simplify the application of reference characters to the numerous contacts appearing in the drawings.

For each denominational order there is also provided a set of four relay magnets designated Ri, R2, R4 and R8, with each of which is associated a series of contacts designated by lower case letters and which will be similarly identified as, for example, RBaR or RliaL as the case may be. These relay magnets are of the type which shift their contacts upon energization and enable the contacts to return to the normal positions shown upon deenergization.

In the lower left hand corner of Fig. 4 is shown a relay magnet designated ST which is common to all denominational orders and upon energization shiftsthe series of contacts in horizontal alignment therewith and extending through Figs. 4, 4a and 4b.

Immediately above magnet ST is a magnet designated SC which is of the same type as the accumulating magnets A. This magnet is also common to all orders and operates the series of contacts extending through the three figures of the circuit diagram. The movable blades of this series of contacts are normally in their left hand positions as indicated, so that upon the deenergization of this magnet following the first energization thereof the related contacts will be shifted to the right.

A further relay magnet designated SA is provided which is of the slow acting type such that its contacts a close after an interval of time determined by the characteristics of the magnet.

For each denominational order there is provided aset of digit representing lamps generally designated 25, and for the entire apparatus there are provided two lamps 26 and 21 (Fig. 4) which indicate whether the amount standing in the accumulating relays is negative or positive, re-

spectively. v

In each order of the accumulator the four magnets AI, A2, A4 and Al may be considered as having a set or an unset position or condition. These magnets by their condition represent in combinational manner the ten digits. The particular combination is that of the binary system of notation, and for this reason the magnets are designated with the numerals 1, 2, 4 and 8 to indicate the terms of the binary progression with which the magnets are in correspondence. Thus, the digit 1 is represented on the magnets by the setting of magnet AI, the digit 2 by the magnet A2, the digit 3 by magnets AI and A2, etc. The setting of thecomplete series of digits and numbers within the capacity of the four magnets may be thus tabulated as follows where X indicates a set condition and a dash represents the unset condition:

Accumulating magnets A8 A4 A2 A1 In handling a problem involving subtraction which may result in negative balancesthe digits and numbers will be represented on the accumulating magnets in the form of complements and the several digit representing settings will be as follows:

Accumulating magnets Digits A8 A4 A1 X X X X X X X X X X X X X X X X X X X X X X X x x X X x I X x It is to be noted that in accordance with the foregoing table the digits'are complemented to the value 15, which is the greatest amount that may be represented on all four magnets Al to At. It is also to be notedthat the complement of the digit is represented by a complemental settingof the accumulating magnets. For example, where a magnet or magnets are in set condition for a particular digit, the same magnets are in unset condition for the complement of that digit. It may also be mentioned at this time that the circuit arrangement is such that, when a complementary value is set on the accumulating magnet, the lamps 25 will nevertheless display the true value of the digit represented and the negative sign lamp IE will serve to indicate that this is a negative amount.

Indicating circuits with the machine clear I With the machine in reset or clear condition, the lamps 25 .will be illuminated to represent zeros and the lamp 21 will be illuminated to indicate the positive sign. The various contacts in the circuit diagrams of Figs. 4, 4a. and 4b are shown in the position they occupy when the machine is clear and current is supplied to positive side of line designated IIS and the negative side of line designated I20. With current on these twolines, a circuit is traceable from line I20 (Fig. 4), lamp 21, wire I30, to contacts SCdL (representing the left hand d contacts of the magnet SC) and thence to positive line IIG. Thus, the spins lamp 2! is illuminated. In each of the three orders a further circuit is also traceable from negative side of line I20, zero lamp I25, contacts AIvR, AZuR, AdmR, AIlgR, wire I", contacts SCdL to positive line I I6.

Fig. 5 represents the. condition of the accumulating relay magnet during various calculations which are now to be explained in detail. In the figure the X's represent the set condition of the accumulating magnets and the dashes represent the unset condition, while the lamps indicate the true value of the amount together with its algebraic sign. The first line designated clear indicates that all of the A magnets are in unset condition, while the lamps represent +000.

The next line of Fig. 5 is headed add 16 which for such operation is simply an entry, inasmuch as no accumulating will result from this first operation.

Entering amount 16 The first step in entering amount I6 is to depress the #1 key I in the tens order (Fig. 4a)

, and the #6 key I in the units order (Fig. 4b).

be latched closed. No circuits are completed at this time. The operator then presses the plus key III which through hell crank II2 (Fig. 4) moves rod Ill toward the left to shift the three sets of related contacts a to d in that direction. Concurrently, the key I08 through bell crank II3 shifts rod II! toward the left to shift the related contacts designated a to t. In the following, the contacts controlled by the rods I I4 and II! will be designated as IllaR or IIlaL to indicate the particular contact in its right hand or left hand position.

The key I" closes its contacts I09a (upper left hand corner of Fig. 4) and upon such closure a'circuit is traceable from the positive nne I I 6, through contacts Ili9a, wire III which extends across Figs. 4a and 4b, where in the latter it continues througn'a group of .vires I6I connected to the key contacts. From here circuits extend through the lower a and 1: contacts of the #6 key through the related one of a group of wires I62 to the left side of the contacts I HI) and c, which are now closed. The circuit then continues through the two central wires of the group desthe R2 and R4 relay magnets. Examination of the circuits through the key contacts and the contacts of rod II4indicate for each of the other digits the R magnets which will be energized in accordance with the appropriate binary combination.

In the tens order a similar circuit extends from the wire II'I, through the lowermost wire IN, the lower a contacts of the #1 key, through the lowermost wire I62, contacts II4aL, through the left hand wire I65, relay magnet RI, wire I64, to line I20. In the hundreds order no circuits are completed, as none of the key contacts are shifted.

Accordingly, magnet RI in the tens order and magnets R2 and R4 in the units order are energized and their related contacts are shifted from the position shown in Figs. 4a and 4b.

It is to be noted, at this time, that with rod II4 in its non-shifted or right hand position the R magnets are connected in complementary manner to the key contacts, so that the complementary value of the digit of any key may be set up on the R magnets. A particular tracing of th .circuits involved will be given later in connection with the subtraction of an amount.

With rod I I5 shifted .to the left, a circuit is also traceable from line II6 (Fig. 4b), wire I40, contacts SCnL, II5tL, wire 209 (Figs. 4a and 4), magnet ST, wire 202 to line I20.

The closure of the key contacts I09a (Fig. 4) also completes a, circuit from line I I6, contacts mm, wire In extending downwardly, the slow acting relay magnet SA to line I20. Upon closure of the contacts SAa, a circuit is traceable from line I I6, contacts SAa, wire, I63 (Figs. 4a, 4b) to the contacts IISsL, contacts SCkL, RImR, R2qL, R40L, A4hR, R8gR, ABe'R, wire I42, contacts II5eL, contacts right hand winding of magnet A2, contacts AEJR, R4fL, the right hand winding of magnet A4, contacts A IdR, contacts RBdR, wire I46 (Fig. 4a), contacts I I5nL, contacts SClcL, RI mL, AIiR, R2qR, A2nR, R4pR, A4iR, RBhR, wire I48, contacts II5eL, contacts STaL, SChL, RIhL, right hand winding of magnet AI, contacts AIeR, R2hR, R4JR, RBdR, wire 200 (Fig.4), contacts 50L, SCkL, RImR, R2qR, A2nR, R4pR, A4iR, RBhR, Wire 20I, contacts II 5eL, S'IaL, SChL, RIhR, R2hR, R4fR, RBdR, wire 202 to line in.

In this manner upon closure of the contacts of the slow acting relay SA, after the R relays have been adjusted in accordance with the amount 16,

' a so-called accumulating circuit is completed in which circuit is included a winding of magnets A2 and A4 of the units order and magnet All of the tens order. Energization of these A magnets will shift the related units from the full line position of .Fig. '2 to the dotted line position of the same figure without disturbing the setting of the related contacts. Upon release of the plus key STy'L, SChL, RlhR, R2hL,.

follows.

I09 magnet SA will become deenergized and open its contacts SAa so that the series'circuit just traced will be broken and the A magnets will become deenergized, whereupon the related parts will shift to the position shown in Fig. 3, leaving the three selected A magnets in their set position. This is indicated along the line designated add 16 in Fig. 5. The release of the plus key I00 will also open the contacts I09a, so that the R relays will become deenergized and the rods H4 and I I5.will also return to their right hand positions, returning their related contacts to the position shown in the circuit diagram.

As a result of the setting of the A magnets in accordance with the value 16, circuits are now established to cause the indicating lamps 25 to represent +016. These circuits are traceable as For-the digit 6 in the units order the circuit is traceable from negative line I20, the #6 lamp 25, contacts AIpR, A2sL, A4mL, A8gR, wire I30 (Figs. 4 and 4a), contacts SCdL, to line us.

In the tens order the circuit is traceable fromline I20, the #1 lamp I25, contacts AIvL, AZuR, A4mR, A8gR, wire I30, to line II6 as before. In the hundreds order the circuit is traceable from line I20, the zero lamp I25, contacts AIvR, AZuR, A4mR, A8gR, wire I30,toline H6. The plus lamp 2'! is also illuminated through the circuit from line I20, lamp 21, contacts SCdL, to line II6.

It will thus be noted that the setting of the R relay magnets in accordance with the amount to be entered, adjusts the contacts of the R magnets to permit the completion of a single continuous circuit to directly energize the accumulating magnets A in accordance with the entered value and that the A magnets in turn, upon the setting of their contacts, adjust the related contacts for the completion of circuits to the indicating lamps 25. The purpose in providing the slow acting Entering the amount 9 Following the chart of Fig. 5, the amount 9 is now to be added to the amount 16 set in the accumulating relay magnets. Again as before, the operator depresses the 9 key I in the units order and the zero key in the tens order, this latter setting being to release the previously latched 1 key. The plus key I09 is now depressed to shift the rods II4, II5 to the left and shift the a, b, c, and d contacts of the rod II4. Upon closure of the contacts I09a a circuit is completed to energize the magnets RI and R8 in the units order.

This circuit is traceable from line II6 (Fig. 4),

contacts I09a, wire I8 I (Figs. 4a and 4b), the uppermost wire I6I, the upper a contacts of the 8 key, the lower a contacts of the 9 key, contacts il4dL, right hand wire I65, relay magnet R8, wire I64, line 820. A parallel circuit extends through the lowermost wire I 6|, upper a contacts of the 1 key, upper b contacts of the 3 key, upper b contacts of the 5 key, upper 0 contacts of the 7 key, lower 19 contacts of the 9 key, contacts II4aL, left hand wire I65, relay magnet RI, wire I64, to line I20.

In the tens and hundreds orders no circuits are completed since no significant digit is set up in these two orders. The magnet ST is again energized through the circuit already traced, upon shifting of contacts II5tL (Fig. 4b).

When the slow acting relay contacts SAa close,

a circuit is traceable from line II6 (Fig. 4), contacts SAa, wire I64 (Figs. 4a and 41)), contacts IIs'L, SCkL, RImL, AIiR, R'ZqR, A211L, R IOR. R8913, wire I43, contacts IISdL, SThL, SCoI, RIjL, winding of magnet AI, contacts AIdR, R2JR, winding of magnet A2, contacts A2eL. R4dR, RBcL, wire I41 (Fig. 4a). contacts II5mL, SCiL, RIiR, AIjL, R2z'R, RfihR, RBeR. A8dR, wire I50, contacts II5cL, STIL, SCjL, RIgR, winding of magnet AI, contacts AIeL, R2gR, winding of magnet AZ, contacts A2fR, RlfR, RBdR, wire 200 (Fig. 4), contacts IISIIL, SCkL, RImR, RZqR, AZnR, R4pR, AMR, RShR. wire I, contacts II5eL, STjL, SChL, RIhR, R2hR, RlfR, R4dR, wire 202 to line I20.

Included in the circuit just traced are windings of the magnets AI and A2 in the units order and magnets AI and A2 in the tens order. Upon release of the plus key I09 this circuit is broken and the said A magnets will shift their contacts to the alternate position, that is, those,

that are already in set position will shift to unset position and those that are in unset position will shift to set position. Thus, the magnet AI in the units order will shift its contacts to set position, the magnet A2 in the units order will shift its contacts back to the unset position, the magnet AI in the tens order will shift its contacts back to unset position, and the magnet A2 in the tens order will shift its contacts to set position so that, as shown in Fig. 5 along the line designated add 9, the setting of the accumulating ma nets A will be in'accordance with the value represented by a setting of magnet A2 in the tens order and magnets A4 and AI in the units order.

In the tracing of the circuit for energizing these magnets, it is to be noted that prior to the adding of the amount 9 magnet A4 in the units order was in set position, and this setting remained undisturbed.

From the explanation of the manner in which the amount 9 is added to the amount 16, it is to be noted that the previous setting moves directly to the setting representing the accumulated amount, that is, immediately upon release of the plus key I09 the A magnet contact settin s move directly from that represented along the line "add 16" to the setting represented along the line "add 9." Also the indicating circuits shift accordingly to display the amount standing in the device. These indicating circuits are traceable as iollows: in the units order from line I20. the 5 lamps 25, contacts AIrL, AzsR, A4mL, ASQR, to wire I30. In the tens order from line I20. the 2 lamp 2!, contacts AItR, AzuL, A4mR, A8gR, to wire I30. In the hundreds order from line I20. the zero lamp 25, through the circuit already traced to wire I30, and from thence through the contacts SCdL to line I I8. 1 At the same time the plus lamp 21 is also illuminated through the circuit already traced.

It will be noted that when two digits are combined in an order of the accumulator, the circuit will extend through the wire I42 (Fig. 4b) of the units order when the sum of the two digits to be combined in less than 10, that is, incases where no tens carry is required, the circuit extends through the wire I42. Where the sum oi the two digits is greater than 9, the circuit extends through the wire I43. These two conditions are illustrated by the example chosen where in the units order 6 was first combined with the zero and the circuit traced through wire I42, while in the second example}; added to the 6 standing in the units order involved the tracing of the circuit through wire I43, which inspection will show has the effect of adding a corrective 6 to the binary sum of 6 and 9, and at the same time adds a corrective or carry 1 to the higher order which, expressed as binary numbers, -are as follows:

As seen, the sum of two units order digits is 15 which, however, must be corrected to represent 5 and a i must be added to the tens order. This would be done mathematically by adding the correctives 6 and 1 as shown so that the result would be the binary expression for 25. The wire I43 leads the accumulating circuit through the contacts of the R and A magnets so arranged that these correctives 1 and 6 are taken into account and the final result is directly obtained.

I In the higher orders the action is similar, that is, the wires I48 (Fig. 5a) and 20! (Fig. 4) correspond to the wire I42 of Fig. 4b and the wires I49 (Fig. 4a) and 203 (Fig. 4) correspond to wire I43 (Fig. 4b). Inspection will also show that, if no tens carry is called for in the units order, the circuit continues through the wire I46 (Fig. 4b) which in Fig. 4a. corresponds to the wire I63 of Fig. 4b and from this point the circuit extends through the wire I48, if no carry is called for in the tens order, and through wire I49 if the sum of the digits in the tens order is greater than 9. Where there is to be a carry, for example, from the units to the tens order, the circuit in Fig. 4!) extends through the wire I41 which then extends through the wire I50 in Fig. 4a as tracedin connection with the example 16+9.

This has the effect of adding 1 to the value in the tens order. If this tens order is already set at 9, there occurs what is known as the carry on carry" condition which requires that a 1 be carried to the next higher order. In such case the circuit extends in Fig. 4a to the wire 204 and to the hundreds order where it passes through contact settings arranged to increase the sum of the digits in such order by 1.

Carry on carry circuit A specific circuit will now betraced to illustrate the carry on carry condition. Let it be assumed that the accumulator is standing at the amount 93 and that the amount '7 is to be added thereto. In the units order, therefore, the '7 added to the 3 standing therein will total 10 and the 9 has nothing added to it in the hundreds order. To obtain the setting of representing the sum of 93 and '7, it is necessary to in effect add a 6 in the units order, a 7 in the tens order, and a 1 in the hundreds order. The problem here involved is analyzed in Fig. 6 wherein the setting of the A magnets for the initial amount 93 is represented and below is shown the setting of the R. magnets for the value 7 which is to be added. If the digits in the separate orders were combined without carry between orders, the setting in the units order would result in a setting representing 10. in the tens orofl in the hundreds order.

To indicate how these correctives are automatically taken care of in the contact arrangement of the various A and R. relay magnets, the particular circuit involved in the problem of Fig. 6 will now be traced with the assumption that the A magnets are set in accordance with the value 93 and the R relay magnets have been set in accordance with the value 7 and the plus key I09 in Fig. 4 has been actuated so that rods i I4 and I I are to the left and magnet ST is energized as already explained. This circuit is emphasized in heavy lines on the circuit diagram to facilitate its tracing: from positive side of line H6 (Fig. 1), contacts SAa, wire I63 (Figs. 4a, 41)), contacts H.5sL, SCIcL, RimL,

'AliL, R2221, AZmL, RAnL, wire H3 (since a tens carry is called ,for), contacts IlSdL, SThL, SCgL, RIfL, winding of magnet Al (this returns the magnet Al to unset condition), contacts AldL, RZeL, winding of magnet A2 (this returns the magnet A2 to unset condition), contacts AZdL, R4cL, R8bR, wire I47 (since a tens carry is called for), contacts ll5mL (Fig. 4a), SCiL, RIiR, AIfL, RZiR, RdhR, RBeR, AfidL, wire I5I (since a carry is called for), contacts HSbL, STdL, SCeL, RleR, winding of magnet Al (this returns the magnet Al to unset condition), contacts AldL, R2eR, R4dR, RBcR, winding of magnet A8 (this returns the magnet A8 to unset condition), contacts A8cL, wire 204 (since a tens carry is called for), contacts i55fL (Fig. 4), $021., RliR, AlfR, RZy'R, A2hR, R lz'R, AfljR. RBfR, wire 205 (since no tens carry is called for), contacts H5cL, STfL, SCfL, RlgR,'winding of magnet A6 (to set magnet Al), contacts AleR, R2hR, RA R, RBdR, wire 202 to negative side of line I20.

In analyzing this circuit it is noted that for each order the circuit passes through a set of contacts of the A and R magnets, which may be said to inspect the two numbers to be combined in the particular order to determine whether a corrective is to be taken into account or not. -Thus, for the units order the settin of the contacts to direct a circuit through wire M3 determines that a corrective 6 is to be applied to the units order. Thereafter, the circuit extending through wire Ml determines that a corrective 1 is to be appl ed to the tens order, and the setting of the contacts in the tens order extending from the wire Ml to the wire i5l takes into account the fact that this order is standing at 9, and that the addition of 1 will cause this order to pass through 10, so

. that it requires the corrective 6 in addition to the corrective 1, resulting in the ultimate inclusion of the corrective '7 in this order from which it passes through the wire it, through further contacts to th wire 204, which determines that a corrective 1 is to be carried over into the hundreds order.

Through the contacts in the hundreds order extending to the wire 205, it is indicated that no additional corrective other than the one carried from the tens order is required, so that the circuit continues through this wire 205 to enter the 1 in the hundreds order. Since there is no previous entry in this order, only the Al magnet is energized. Inspection will show that, if the order were standing in any other digit, the resultant entry would be 1 greater than the initial setting.

This example serves to illustrate that for the corrective 7, the circuit extends through contacts SCe; for the corrective 6 the circuit ex:- tends' through contacts SCg; for the corrective 1 the circuit extends through contacts SC and for no corrective the circuit extends through contacts SCh.

It is to be particularly noted that for each order the right hand windings of the A magnets with the connected A and R contacts constitute what may be termed a relay chain for adding amounts when the energizing circuit enters through the Rih contacts. That is, this relay chain is effective to alter the A magnet settings when no corrective is to be included in the sum mation.

Subtraction The procedure in subtracting is similar to addin in that the amount to be subtracted is set up on the keys i, 'but this time instead of depressing the plus key I09 the minus key H0 is operated to close its contacts 0a. For sub.- traction, the rods H4 and 5 are not disturbed so that their related contacts remain in the positions shown in the circuit diagram.

A specific example will now be set forth in which the amount 17 is subtracted from the amount 25 standing in the accumulator. This example is indicated in Fig. 5, where it is shown that the amount 17 subtracted from 25 results in the setting of the accumulator to represent I latched. Upon depression of the minus key M0,

the R relays in the several orders will be energized in accordance with the complement of the digit set on the keys, that is, in the hundreds order all four R magnets will be energized, in the tens order magnets R2, R4 and R8 will be energized and in the units order R8 will be energized.

The energizing circuit for the hundreds order extends from positive line M6, to contact Elna, wire HI, wires i511, thence through all four wires, through all the upper key contacts a, b and c, to the contacts la, b, c, andd right,

through the four wires E65, the four R magnets and wire 202 to negative line B20. In the tens order the circuit from wire H1 extends through the three upper wires it, the upper contacts of all the keys except the 1 key, to the contacts iMb, e, d, right to the R8, R4 and R2 magnets,

wire [164 to line 520. In the units order the circuit from Wire H1 extends through only the uppermost wire Mil, the upper a contacts in the 9 and 8 keys, contact iMdR, magnet R8, wire i6 3 to line E20.

Comparison devices ues of the amounts.

net ST in the lower left hand corner of Fig. 4. This magnet is energized through the previously traced circuit whenever two positive amounts are combined but may be energized or deenergized when the signs of the two amounts are different, depending on the relative numerical val- Briefly, the results may be tabulated as follows: Where A represents the balance standing in the accumulator and R represents the amount to be entered, then for the condition A greater or less than R, magnet ST is energized -A greater or less than -R, magnet ST is not energized A greater than R, magnet ST is energized A less than -R, magnet ST is not energized -A greater than R, magnet ST is not energized A esa than +R, magnet ST is energized For each accumulator order there is provided a pair of contacts A8 (Figs. 4, 4a and 4b) and a series of other contacts controlled by the R and A magnets directly below. In the hundreds order the movable contact blade of contacts A8! is connected by a wire 201 to positive side of line I I6 and from the lowermost of this group of contacts in the hundreds order there extends a wire 208 (Fig. 4a) to the contacts A8! in the tens order. From the lowermost group of contacts in the tens order the wire. I35 extends over Fig. 4b to the contacts A8! of the units order. The lowermost contact of the group in the units order has connections to the n and contacts of the magnet SC.

When the amount standing in the accumulater is positive, the contacts of the SC magnet are in the position shown and, when a positive amount is added, the contacts of the rod H5 are shifted to the left, so that a circuit is traceable in F. 4b from line H6, wir I40, contacts SCnL, IIStL, wire 209 (Figs. 4a, 4), relay magnet ST, wire 202 to line I20. This causes all the ST contacts to assume the left hand position when two positive amounts are added together.

If the amount standing in the accumulator is negative, the contacts of the SC magnet are in their right hand position and the circuit through wire I (Fig. 4b) is not completed. Also, when a negative amount is to be entered contacts 5t are in their right hand position so that no ourrent will be supplied to wire 20S and as a result, for this condition the magnet ST is not energized.

When the two numbers added are different in sign, the negative one is represented as a complement on either the A relays or the R relays. Since the digits are represented in a binary system of notation, it is apparent that the relative size of the numbers is indicated by the highest order position in which the related R and A magnets are both set or both unset.

The following examples will serve to illustrate this. Assuming the number +5 set in the A magnets and the number -3 set in the R magnets, the relative setting for these magnets in the two orders may be represented as follows:

Tens Units Amagnetsetting-l-Ofi Rmagnetsetting-Oii X X X X X that both are set is an indication that the positive amount is greater than the negative amount.

Assuming that the positive amount is less than the negative amount, the settings are as follows:

Tens Units A magnet setting +05 R magnet setting 07 X X X X xx--- Tens Units Amagnetsetting 05 X X X X Rmagnetsetting+03 e Here the like setting is in the 4 position of the units order with both magnets in unset condition indicating that the negative value is reater.

Finally, where the negative amount on the A magnets is less than the positive amount on the R magnets, we find:

Tens Units Amagnetsetting05. X X X X X X Rmagnetsetting+o7 X X In this case the like setting is in the 2 position with both magnets in the set condition indicating that the positive valueis greater.

Applying these deductions to the circuit (Figs. 4 and 4a) and assuming a +005 setting on the A magnets and a O03 setting on the R magnets, a circuit is traceable from positive line H6 (Fig. 4), wire 201, contacts A8JR, R8711, A4kR, RluL, AZTR, R2wL, AlmR, RlqL, to wire 208 (Fig. 4a), contacts A8 R, down through the related contacts in the same manner as for the hundreds order to wire I35 (Fig. 41)), contacts A8fR, R87'L, AlkL, RdtL, wire I36, thence to contacts SCoL. HStR, wire 208 (Figs. 4a and 4), magnet ST to line I20.

Assuming now the condition of the A magnets set at +005 and the R magnet at --007, a circuit is traceable just as before to the wire I" (Fig. 4b) and extends through contacts ABIR. R87L, AlkL, RltR, AZrR, mwa, at which point the circuit is terminated so that, for the condition in question, the magnet ST is not energized.

Assuming now for a further example that the A magnets are set at -005 and the R. magnets at +003, the circuit extends from line Hi (Fig. 4) wire 201, through contacts ABIL, RliR, AlkL, RltR, A2rL, RibR. AlmL, RlpR, wire 208 (Fig. 4a), thence down through the same contacts in AllcR, RZuR, at which point this circuit also ter- 'ABIL, RBiR, AlkR, RlaL, AITL, RZ'uL, wire I36,

contacts SCnR, I ItL, wire 209, to the magnet ST to energize the same.

From the tracing of these comparison circuits, it will be seen that where the two numbers are of the same value but different sign in any order, the circuit passes through the comparing contacts to the wire 208 or I35 and, where there is a difference in value, a circuit i completed to energize the magnet ST in accordance with the conditions of comparison and sign enumerated hereinabove.

Subtracting 17 from 25 With the A magnets set to represent 25 and the R magnets set to represent; the complement of 17, as explained above, the circuit will now be traced which causes the setting of 025 as indicated in Fig. 5 to readjust the A magnets to rep resent a setting of 008, Upon closure of the contacts of the slow acting relay magnet SA (Fig. 4), the accumulating circuit extends from positive side of line H6, contacts SAa, wire 163 (Figs. 4a, 4b), contacts IISsR. (since rod H5 is not shifted for a negative entry), contact SCmL, STmL (magnet ST is energized since this is a condition of the positive A amount greater than negative R amount), contacts RIy'R, AIgL, R2kR, AZiR, RMR, R8fL,.ABdR, wire 44, contacts lIScR, STeL, RIcR, windingof magnet rm (to return this magnet to the unset condition), contacts AIcL, RZcR, RAcR, winding of magnet Ad (to return this magnet to unset condition), contacts Adah-R3221, winding of magnet A8 (to' set this magnet). contacts ASZJR, wire i4! (Fig. 4a) contacts Ei5mR, SCy'L, STkL, RInR, RZsL, AEoL, R5914, RSgL, wire hit, contacts llfidR, STgL, RHJR, B21211, winding of magnet A2 (to return this magnet to unset'conditlon), contacts A2291, R tail, R5111, wire 2% (Fig. 4), contacts li5gR, SCmL, STmL, Riy'L, RZRL, R4213, RBeL, wire contacts iltbR, STcL, contacts Rial, R2aL,

vR-iuL, RdaL, wire 202, to negative side or line M0.

Upon opening of contacts SAa, the A magnets take the setting indicated along-the line subtract 1'7" (Fig. 5) and the lamps will indicate the value +008, Analyzing this problem and the circuit traced, we iind that the units order A magnets were set at 5 and that the R magnets were set at 8 (complement of '7) which, when added to 5, would result in 13 requiring a corrective 5 to be taken into account, reducing the 13 to the corrective result 8. In the-tens order the A magnets were set at 2 and the R magnets set at 14 (complement of 1) whose sum resulted in .16 and required no corrective. In the hundreds order the A setting of zero with the setting of 15 complement of zero) on the R magnets would result additively in 15 requiring a corrective -15 With the A magnets set to represent 8 and the keys I set to represent 59, circuits are completed in the now familiar manner upon depression of the minus key H0 to energize the R magnets in accordance with the complement of 59. For this condition we have the positive A amount less than negative R amount, for which condition as explained the relay magnet ST does not become energized, rod II5 remains in its right hand positacts A2jR, RML, winding of magnet A4 (to set the magnet A4), contacts A4dR, RBdR, wire I46 (Fig. 4a). contacts lISnR, SCmL, STmR, RInR, R2sL, A2oR, R4qR, RShL, A8eR, wire I48, contacts IISeR, STiR, SChL, RlhR, R2hL, winding of magnet A2 (to set magnet A2), contacts A'ZfR, R4fR, RadL, winding of magnet A8 (to set this magnet), contacts ABcR, wire 200 (Fig. 4), contacts HSgR, SCmL, S'I'mR, RInL, AljR, R2sL, A20R, R4qL, AHR, RBhL, ABeR, wire 20I, contacts I I5eR. STiR, SChL, RIhL, winding of magnet Al (to set magnet Al contacts AIeR, R2hL, winding of magnet A2 (to set magnet A2), contacts A2 fR, RAIL, winding of magnet A4 (to set magnet A4), contacts A4clR, R8dL, winding of magnet A8 (to set magnet LAB), contacts ABcR, wire 202 to line I20. This circuit conditions the A magnets for shifting to represent the comple men-t of 51 upon opening of the contact SAa.

An additional circuit is also traceable due to the changing sign of the result, which circuit is traceable from the contacts SAa (Fig. 4), through contacts HEaR, S'IbR, SCcL, winding of magnet 50, wire 232 to line I20. This circuit energizes the magnet SC which, as explained, is of the same construction as the A magnets, so that upon its subsequent deenergization it will shift its contacts to their alternate position, which position they occupy whenever the bal ance in the accumulator is negative.

As a result, the minus lamp 26 is now illuminated through a circuit traceable from line I20 (Fig. 4), minus lamp 26, contacts SCdR, to line i it.

The lamps 25 will be illuminated in accordance with the true value of the negative complement and the circuits in the three orders are traceable as follows: for the hundreds order, from line I20 (Fig. 4), the Zero lamp 25, contacts AIwL, AZvL, A4111, .AthL, wire I3I, contacts SCdR, to line I I6. In the tens order the circuit extends from line M0, the 5 lamp 25, contacts AIsR, A2tL, A4uR, ABhL, wire l3I, to line IIB a for the hundreds order. In. the units order the circuit is traceable from line I20, the 1 magnet 25, contacts AIwR. A2vL, A4nL, ABhL, and wire l3l to line IIB as before.

Thus, at the end of this operation the balance 51 is set in the form of a complement onthe A magnets and the lamps indicate the true value -051. This condition of the device is indicated in Fig. 5 along the line headed subtract 59.

Enter -39 The circuits will now be traced for the further subtraction of the amount 39 which with the negative amount 51 standing in the accumulator will result in a setting of as indicated in Fig. 5;

resenting 051. The amount 39 is set on the keys I and the minus key H i depressed. Thus, upon closure of the contacts Il0a in the now familiar manner the R relay magnets are energized in accordance with the complement of the amount 39. Specifically, all the R magnets in the hundreds order are energized, the magnets R4 and R8 in the tens order and the magnets R2 and R4 in the units order are energized with accompanying shift of the related contacts.

During this operation, the relay magnet ST is not energized, since the contacts II5t (Fig. 4b) are in their right hand position and the contacts SCo are also'in their right hand position, so that no circuit can be completed through the'wire 209 which extends to the magnet ST. Accordingly, since both quantities are negative. the comparison circuit is ineffective.

With the contacts of magnet SC, ST and rod II! in their right hand positions, the accumulating'circuit is traceable upon closure of the contacts STa as follows: from line II6 (Fig. 4), contacts SAa, wire I03 (Figs. 4a., 42)), contacts 58R, SCmR, RIkR, AIhR, RL, R4kL, R8fR, wire I44, contacts II5cR, STeR, SCfR, RIcR, winding of magnet Al (to set this relay), contacts AIcR, R2dL, R4cL, RBbR, wire I41 (Fig. 4a), contacts IIS R, SClR. RIoR, R2uR, A2qL, R4rL. RBhL, A8eL, wire 149, contacts IIEdR, STgR, SCgR, RIbR, R2bR, R4bL, winding of magnet A4 (to set this magnet), contacts A4bR, RBbL, winding of magnet A0. (to unset this magnet) contacts A8bL, wire 200 (Fig. 4), contacts lISgR, SCmR, RlkL, R2nL, A27L, R4 L, A4fL, RBeL, wire 205, contacts II5bR, STcR,

,SCeR, RIaL, R2aL, R4aL, R8aL, wire 202 to line Adding 304 to -9c The next line in Fig. 5 shows the result of adding 304. to the negative quantity 90 which results in the setting of the-A relay magnets to represent the positive quantity 214. The first step is to set the amount 304 on the keyboard and to depress the plus key I09. This will result in energization of the R magnets in accordance with the positive value 304. Specifically, in the hundreds order magnets AI and A2 are energized, in the tens order none of the magnets are energized, and in the units order the magnet A4 is energized.

In accordance with the conditions now present where the negative amount standing in the accumulator is less than the posit ve amount to be added, the relay magnet ST will be energized under control of the comparison circuits through which the energizing circuit may be traced as follows: from line IIB (Fig. 4), wire 201. contacts AflfL. RBiR, A4kL, R4tR. A21-L. RZ'vL, to wire I 36 (since in this order both the A and the R relays are set, it is an ind cation that the positive amount is greater than the negative amount). From wire I36 (Figs. 4a, 4b) the circuit continues through contacts SCnR.. IIStL (since the plus kev I09 is depressed), w re 209, magnet ST, wire 202, to line I20.

S nce the sign of the result is to change from minus to plus. the magnet SC isalso ener ized at this time to prepare its contacts for shifting back toward the left after the accumulating circuit has been broken. This energizing circuit is traceable from line I20, wire 202, winding of magnet SC, contacts SCbR, STaL, IISaL, contacts SAa, to line 0.

The accumulating circuit is traceable as iol lows: from line H8, contacts SAa (Fig. 4), wire I03 (Figs. 4a, 4b), contacts IIIsL, SCkR, STmL, RIyR, AlaL, RZkR, A2iL, R4iL, RleR, AldL, wire I45, contacts IISbL, STdL, SCeR, RIaR, winding of magnet AI (to unset this magnet), contacts AIbL, R2aR, winding of magnet A2 (to unset this magnet), contacts A2bL, R4aL, contacts RBaR, winding of magnet A8 (to unset this magnet), contacts ABbL, wire I48, (Fig. 4a), contacts IISnL, SCkR, STmL, RIjR, AIgR, R2mR, R47R, R8jR, wire I50, contacts IllcL, STfL, SCjR, RIcR, winding of magnet Al (to set this magnet), contacts AIcR, R2dR, winding of magnet, A2 (to unset this magnet), contacts A2dL, R4cR, winding of magnet A4 (to unset this magnet), contacts -A4cL, contacts RObR, wire 204 (Fig. 4), contacts 51L, SCiR, STkL, RInL, AIiL, R2rL, R4pR, A4iL, RBgR, AOeL. wire 203, contacts II5dL, SThL, SCgR, RIbL, winding of magnet Al- (to unset this magnet), contacts AI bL, R2aL, R4aR, winding of magnet A4 (to unset this magnet), contacts A4bL, ROaR, winding of magnet A8 (to unset this magnet), contacts ABbL, wire 202 to line I20.

This circuit will cause readjustment of the setting of the A magnets in accordance with the total 214 as indicated in Fig. 5. Upon release of the plus key I09, the readout contacts of the A magnets will take position to complete circuits through the lamps to represent +214.

Subtracting 25 from 25 Circuits will now be traced to show what takes place when two equal numbers of opposite sign are combined. It will be assumed that the A magnets are set to represent 25, the keys I are set to also represent 25 and that the minus key H0 is depressed. As a result, all the R'relays in the hundreds order will be energized, the RI. R4 and R8 relays in the tens order will be energized, and the R2 and R8 relays in the units order will be energized.

A circuit is then traceable from line H8 (Fig. 4), wire 201, contacts AIlfR, R8713, A4kR, R4uL, AZrR, R2wL, AImR, RiqL, wire 208 (Fig-4a), contacts A8fR, R87L, A4kR, R4uL, A2RL, R2vR, AImR, RIqL, wire I35 (Fig. 4b), contacts ABfR, R81'L, A4kL, R4tR, A2rR, R2wL, AImL, RIpR, SCoL, IIStR, with 209 (Figs. 4a and 4), relay ST, wire 202 to line I20. If the A value had been negative and the R value positiveflthe circuit would have gone through contacts SCnR, and II5tL, to also energize relay ST. Thus, whenever the two amounts are alike in value, but ditierent in sign, relay ST is energized.

For the problem being considered, upon closure of the contacts of the slow acting relay SA (Fig. 4), the accumulating circui extends from positive side of line H8, contacts SAa, wire I 83 (Figs. 4a and. 4b), contacts IIisR (since the R value is negative), contacts SCmL (since the A value is positive), contacts STmL (since relay ST is now energized), contacts RIgR, AIgL, RZkL, RQZ'R, A4fL, R8eL, wire I45, contacts I ISbR, STcL, RIaR, winding of relay AI, contacts AIbL, R2aL, R4bR, winding of relay A4, contacts AtbL, l-tBaL, wire I48, (Fig. 4a), contacts IISnR, SCmL, STmL, RIjL, R2kR, A2iL, R liL, RBeL, wire ISI, con ctr; 521R, STcL, RIaL, R2aR, winding of rel contacts A2bL, R4aL, RZaL, 25% (Fig. i), contacts 50R, SCmL, STmL,

ascaaso contacts S'I'a and STD (Fig. 4) and, it will be noted that, when contacts SAa close, no circuit is traceable to relay SC with the result that the SC contacts remain in th position shown and the lamp 2'! is lighted.

For the alternative condition, where the A amount is negative and relay SC accordingly with its contacts shifted, a circuit is traceable from line 1 l5, contacts SAa, i laL (since the R amount .ls positive), S'I'aL, SCbR, winding of relay SC,

wire 202 to line I29. As a result, when contacts SAa open, the relay SC shifts back to its positive position as shown in Fig. 4 and its contacts SCd light positive lamp 2! and also feed current to wire i353 to illuminate lamps to represent 000.

Resetting the accumulator It is to be noted in the wiring diagram that for each of the A magnets there is a pair of a contacts which are closed when the related ma net is in set condition. When it is desired to clear the machine, the key Ell (Fig. ll is depressed to close its contacts i l to. This will complete a .circuit from line lit, contacts Mia to wire 2w, which in Fig. 4 extends in parallel to the left hand winding of all of the A magnets, and for those in set condition the circuit will continue through the a contacts to Wire 2632 and line till. In Fig. 4a wire till extends to the similar left hand windings of the A magnets and for those in set condition, parallel circuits extend through their a contacts to wire led and line lid. Likewise, in the units order wire i on tends in parallel through the left hand windings of the A magnets, the a contacts of those in set position, andwire ltlfi to line E29. In this mar her all the A magnets that are set are energized upon depression of the clearing key l i E, and upon release of the key and opening of the contacts iiia the A magnets will advance to their unset position so that they are now all unset, and the readout contacts will be in a posiiton to complete circuits through the zero lamps 25 and the circuit is also completed through the plus lamp 2? as already traced.

If magnet SC is in set position, the closure of the reset contacts Illa will also complete a circuit from line H6, contacts lilo, wire 250, contacts SCaR, winding of magnet SC, to line E20.

From the foregoing it is apparent that the entry of a number into the accumulator additively or subtractively requires only the setting of the number on the keyboard and the depression oi the appropriate key I09 or H0. This has the effect first of setting up the number on the R relays and also energizing the slow acting magnet SA which initiates the establishment of the so-called "accumulating circuit, a number of which have been traced for the different examples. This circuit extends serially through all the orders of the accumulator through the single impulse initiated by the slow acting magnet contacts SAa, and effects .the adjustment of the accumulating magnets A to represent the new result either as a positive or negative balance.

The arrangement of Figs. 7 and 7a In Figs. '7 and 7a is shown an arrangement of the accumulating circuits by means of which each order may be adjusted to handle fractions of any denominator up to 16. For this purpose the keyboard is provided with sixteen keys i in each order corresponding to the ten keys of Fig. 4 and the contacts operated by these keys are similarly arranged to enter either the direct binary equivalent of the number into the R relays or the complement, thereof just as for the form already explained. The same A and R relays as well as the SC, ST and SA relays are provided as well as the same clear and readout circuits which in Figs. 7 and 7a are identified in the same manner as in the circuit diagram of Figs. 4, 4a and 4b.

In connection with the readout circuits there is a greater number of lamps 25 provided which calls for a greater number of controlling contacts as is obvious. The same add, subtract and clear keys I09, H0 and Ill, respectively, are provided which operate in the same manner as in the form already described. The difference between the two circuits lies in the fact that in Figs. '1 and 7a there are provided four additional relay magnets generally designated C. each of which controls a group of contacts shown at the right thereof. The magnets in any order are energized through circuits to be traced later, in accordance with the value of the fraction to he handled by the particular order. This energize.- tion is effected under control of a set of four cams designated 30!, 302, 304 and 393, which are mounted upon a common shaft indicated at 309 on the extremity of which there is a handle and pointer did, by means of which the shaft may be turned to any one of the numbered positions represented on the dial 5i i.

The cams are provided with low and high portions which cooperate with contacts generally designated by the reference character of the cam followed by the sumx a. When the high point of any 'cam is along a horizontal line, it shifts its contacts from the position shown in Fig. 7 toward the left. In the following table there is indicated the contacts that are shifted for each different setting of the cams:

The function of the C magnets is to effect an adjustment of the accumulating circuits, so that the proper tens carry and corrective requirements will be taken into account for the different fractions that may be handled by any order. The contacts 3am to 308a may energize their related C magnets when either in their left hand or right hand position through circuits extending from either a wire I for the left hand side or wire 589 on the right hand side.

The manner in which circuits are completed through wires I89 and ISO will be explained in connection with the tracing of particular problems hereinafter. Suflice it to say at the present time that, when a circuit is completed to wire Entering 1 foot and 8 inches An example will now be given involving the handling of twelfths (inches) in the lowest order, and thirds (feet) in the next order.

As a preliminary, the dial 3I0 in the lowest order is set to the numeral 12 rotating the cams 3M to 388 so that the contacts 384a and 308a are shifted to their left hand position. The tens order dial is set to numeral 3 and as a result the re lated cams shift the contacts 30Ia and 302a to their left hand position. The plus lamp 21 and the zero lamps 25 are illuminated through circuits corresponding to those already traced in connection with Fig. 4, so the tracing of these circuits will not be repeated herein.

The operator.depresses the #8 key I in the right hand order designated unit for convenience and the #1 key I in the left hand order designated "tens for convenience, although it is to be borne in mind that these two orders now represent inches and feet, respectively, for the operations about to be explained. The plus key I08 is first depressed and circuits are completed through the key contacts to energize the RI relay magnet in the tens order and the R8 magnet in the units order, the two circuits corresponding to those already traced, so much need not be repeated at this time.

The operation of key I09 has shifted its rod 5 I5 toward the left, so that a circuit may now be traced from line I I6 (Fig. 7a), wire 240, contacts SCrL, contacts iI59'L, to the wire I89. From this Wire the circuit continues in the units order, through the left hand contacts 301 c and 302a in parallel, magnets CI and C2, wire I54, to line I20. In the tens order the circuit continues through wire I89 to the left hand contacts 304a and 30841 in parallel, magnets C4 and C8, wire 202, to line I26. Thus, just prior to the closure of the slow acting relay contacts Site, the relay magnets RI, C4 and Cd in the tens order are energized and the magnets RS, Cl and C2 in the units order are energized with the resulting shift of their related contacts. This provides a circuit path completed-upon closure of the contacts SAa for setting the value 1 foot 8 inches on the accumulating magnets.

Magnet ST is energized at this time over a cir cuit from line H6 (Fig. 7a), wire 240, contacts SCnL, IIShL, wire 209 (Fig. 7), magnet ST, wire 202 toline I20.

The accumulating circuit path is traceable as follows: from line H6 (Fig. '7), contacts 84%, wire I83 (Fig. 7a), contacts 59L, SCkL, C IJL, RInR, CZhL, R'ZqR, C4hR, R ITR, AM'R, CBiR,

RBmL, ASQR, wire I42, contacts II5eL, STiL,

SChL, RIhR, R2hR, RAhR, R8dL, winding of magnet A8 (to set this magnethcontacts A8cR, wire I46 (Fig. 7), contacts 59L, SCkL, CUR, RIoL, CZhR, RZTR, AZjR, can, turn, Amt, CBiL, RBkR, A8gR, wire I48, contacts II ieL, S'Ia'L, SChL, RIhL, winding of magnet AI (to set this magnet), contacts AIeR, contacts R2hR, RAZLR, R8dR, wire 202, to line I20.

Upon release of the key I 09 and opening of contact SAa, the two magnets, AI in the tens order and A8 in the units order will shift their contacts to their set position and the indicating lamp circuits will be completed to indicate +1 8.

Add 5 inches to 1 foot 8 inches The manner in which circuits are adjusted to add 5 inches to the amount now standing in the accumulator to obtain the result 2 feet 1 inch will now be explained. The keyboard is adjusted to setup zero in the tens order and 5 in the units order and, as for the previous entry, upon the depression of the plus key '39 the relay magnets R4 and R5 in the units order are energized and also the magnets Cl and C2. In the tens order no R magnets are energized, but the C4 and C0 magnets are energized as before through the circuit extending over the wire I89. Magnet ST is also energized as before.

With the slow acting relay contacts S'Aa now closed, the following circuit, which is emphasized in heavy lines, is traceable: line H6 (Fig. 7), contacts SAa, wire I33 (Fig. 711), contacts IISgL, SCIcL, CIfL, RInL, AIiR, CZhL, RZqR, CULE, RATL, C8hR, RBIcR, ABQL, wire I43 (this being the tens carry wire), contacts IISdL, STILL, SCgL, CIbL, RIdL, winding of magnet AI (to set this magnet), contacts AIcR, CZbL, RZdR, ClbR, R IeL, C8bR, winding of magnet A8 (to unset this magnet), contacts ABcL, wire I41 (this being the tens carry wire to the next order), the contacts II5fL (Fig. 7), contacts SCz'L, CIdR, RIiR, CZeR, R2kR, AZgR, CUL, RMCR', AAgR, C8fL, RagR, ABeR, to the non-carry wire I50, contacts II5cL, STIL, SCfL, RIgR', winding of magnet Al (to unset this magnet), contacts AIcL, contacts RZgR, winding of magnet A2 (to set this magnet), contacts AZeR, RfihR, RBdR, wire 202 to line I20.

Through this circuit the setting of the A magnets is changed to represent 2 feet 1 inch. The incidental indicating circuits are similar to those already traced and result in the lamps displaying the Value +2 l.

Subtracting 1 foot 11 inches from 2 feet 1 inch A subtracting operation with the device set for handling feet and inches will now be explained to show how the circuits take care of subtracting conditions. The operator first sets up the tens or feet keys to represent 1 and the units or inches keys to represent 11. Upon depression of the minus key I50, the R magnets in the tens order will "be energized to represent the complement of 1. Specifically, the relay magnets R8, R6 and R2 are energized. In the units order the magnets are energized to represent the complement of 11 represented by energization of the relay magnet R6.

The C magnets are now energized in a different manner than when adding. Current therefor is obtained through the comparing contacts through a circuit traceable from line I I6 (Fig. '7), wire 201, contacts ABhR, RL, AlmR, R4wL, A2mL (since this magnet is set), contacts RZvL to the wire I36 (Fig. 7a), contacts SCqL, IIEiR, wire I00 which in the units order continues the circuit in parallel through the contacts 304a and 8080 to energize the relay magnets Cl and C8.

The circuit from wire I in Fig. 7 continues through the contacts 30m and 302a in parallel to energize the magnets CI and C2 in that order. This comparison circuit by extending through the wire I36 is indicative that the amount to be entered is less than the amount standing in the accumulator, so that the resulting sign will be that of the amount standing in the accumulator,

plement of the values set on the keys.

namely, positive. Magnet ST is also energized through the samecircuit-from wire I36, contacts SCoL (Fig. 7a), II5hR, wire 209, magnet ST to line I20.- As explained for the decimal system, energization of magnet ST is determined by the relative values and signs ofv the two amounts to be added. 1

, Just prior to the closing of the slow acting relay contacts SAa, the following magnets have their contacts in set position:

For the tens order: A2, R8, R4, R2, CI, C2 For the units order: AI, R4, I C4, C8

Upon closure of the contacts SAa, the accumulating circuit will now 'be established to change the setting representing 2 feet 1 inch to a setting representing 2 inches, which is the new balance. This circuit is traceable as follows: contacts SAa (Fig. 7), wire I63 (Fig. 7a), contacts II5gR, SCkL, STmL, RImR, AIhL, RZnR, AZhR, RloL, A4HR, RahR, wire I44, contacts II5cR, STeL, CIbR, winding of magnet AI (to unset this magnet), contacts AIdL, CZbR, RZeR, winding of magnet A2 (to set this magnet), contacts A2dR, CIIcL, RdeL, C8bL, RBbR, wire I41 (Fig. 7), contacts iISfR. SCiL, STkL, RIqR, RiuL, AZkL, RdtL, R8kL, wire 555, contacts IISdR, S'IgL, RIbR, winding of magnet A2 (to unset this magnet), contacts AZDL, R iaL, RBaL, wire 202 to line I20.

As a result the magnet A2 in the units order alone is set and the lamps indicate 2.

Entering the negative amount 2 feet 3 inches The circuits involved in obtaining the negative amount will now be explained to show the manner of obtaining the negative result when 2 feet Sinches are subtracted from 2 inches. The keys are set to represent 2 in the tens order and 3 in the units order; and the negative key lid is depressed which in the now familiar manner will cause energization in the tens order in relay magnets R8, R and Bi and in the units order R8 and R8. These magnets represent the com- The comparison circuit in Fig. 7 follows from line H5, wire contacts ANLR, Riioll, AdmR, RdwL, A2mR, RZwL, AImR, RisR, to a wire 23% (Fig. 7a), and thence throughcontacts SCsL, IIE 'R, wire I39, to energize the magnets Ci, C2 in the units order and C5, C8 in the tens order as already explained. At this time no circuit extends through the magnet ST, since the A value is positive and less than the negative R value, so that a circuit may be traceable later when contacts SAa close to energize the winding of the magnet SC. This circuit is traceable from conmagnethcontacts AlcR, wire '(Fig. 7), contacts R, SCmL, STmR, RIqL, AlkR, RZuR,

RiuL, AlkR, RlmL, AlgR, wire I, contacts iiSeR, STiR, SChL, RIhL, winding of magnet Al (to set this magnet), contacts AIeR, RZhR, RlhL, winding of magnet A! (to set this magnet), contacts AleR, contacts RBdL, winding of tact SAa to contacts I ISaR, S'I'bR, SCbL, winding For the tens order: R8, R4, RI, C4, C8 For the units order:"A2, RLRJ, CI, C2

The circuit extends from contacts SAa, wire I63 (Fig. 7a), contacts II5gR, SCmL, STmR, RIqR, RluR, RluL, AlkR, RSmL, A8qR, wire I42, contacts IISeR, STiR, SChL, RIhR, RZhR, RAhL, winding of magnet R4 (to set this magnet) contacts RScL, winding of magnet A8 (to set this n magnet A8 (to set this magnet), contacts AlcR, wire 202 to line I20. This circuit accordingly energizes additional accumulating magnets to set up the complement of the result 2 feet 1 inch upon the release of the subtracting key. The release of this key is also followed by the representation of 2 feet 1 inch on the lamps 25 as well as the illumination of the minus sign lamp 2, through circuits sufllciently traced hereinbefore, so that the same .need not be repeated at'this time.

The handling of any of the other fractions from halves to sixteenths may readily be followed on the circuit of Fig. 7 or 7a in the manner similar to that just traced for the handling of twelfths and thirds required for the adding and subtraction of feet and inches. Generally speaking, the fraction selecting dials are first positioned to adjust the C magnet selecting cams. The numeral keys are set in accordance with the values to be entered and then the plus or minus key is operated. Following the operation of the plus or minus keys and before the slow acting relay magnet completes the accumulating circuit, the C magnets are energized under control 01' the comparison circuits and the ST magnet is also energized or not, depending On the conditions of comparison and the signs of the two amounts to be combined.

Just prior tc'this, the R magnets are energized in accordance with the true or complementary value of the amounts set on thekeyhoard, depending on whether it is to be entered additively or subtractively. with these preliminary settings taken care oi, the accumulating circuit then follows seriatim through the several orders to directly energize the A magnets to represent the result of the computation. It is to he noted that such A magnets as are already set and whcss setting is called for in the result are not turbed, while those that are set and whose setting is not called for in the result are retinned to unset position or such settin s erased Finally, after the computations are completed, the depression of the clearing key iii byclosing its contacts IIIa will send an impulse to all of the A magnets in the same manner as explained for the circuit of Fig. 4 to restore the entire apparatus to home or zero condition.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a single modification, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. Itis the intention therefore to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. In a machine of the class described, an'electrical relay accumulator comprising a plurality of accumulating relays arranged in sets with each set representing a denominational order of the accumulator, groups of contacts, one group for each relay, adjustable in either a set or unset condition. with numerical values being repre- 

